This application relates generally to gas turbine engines and, more particularly, to methods and apparatus for cooling gas turbine engine rotor assemblies.
At least some known rotor assemblies include at least one row of circumferentially-spaced rotor blades. Each rotor blade includes an airfoil that includes a pressure side, and a suction side connected together at leading and trailing edges. Each airfoil extends radially outward from a rotor blade platform. Each rotor blade also includes a dovetail that extends radially inward from a shank extending between the platform and the dovetail. The dovetail is used to mount the rotor blade within the rotor assembly to a rotor disk or spool. Known blades are hollow such that an internal cooling cavity is defined at least partially by the airfoil, platform, shank, and dovetail.
During operation, because the airfoil portions of the blades are exposed to higher temperatures than the dovetail portions, temperature mismatches may develop at the interface between the airfoil and the platform, and/or between the shank and the platform. Over time, such temperature differences and thermal strain may induce large compressive thermal stresses to the blade platform. In addition, if the blade platform generally is fabricated with a greater stiffness than the airfoil, such thermal strains may also induce thermal deformations to the airfoil, as the airfoil is displaced in response to the stresses induced to the shank and platform. Moreover, over time, the increased operating temperature of the platform may cause platform oxidation, platform cracking, and/or platform creep deflection, which may shorten the useful life of the rotor blade.
To facilitate reducing the effects of the high temperatures, within at least some known rotor blades, at least one of the pressure side and/or suction sides of the platform is formed with a recessed slot which facilitates channeling airflow from a shank cavity defined between adjacent rotor blades for use in cooling the platform trailing edge of an adjacent circumferentially-spaced rotor blade. Although such slots do facilitate reducing an operating temperature of an adjacent rotor blade platform trailing edge, such slots may induce stresses into the rotor blade in which they are formed.